It is an interesting "development"- but more prosaically, might reflect that VFDs (one of my favourite display technologies and one of the last outposts of thermionics!) are a diminishing market and teensy-weensy triodes represents a relatively low-risk toe-in-the-water in a market that craves "toob sound". It's obviously based on existing VFD fabrication techniques and experimenters have been exploiting the triode nature of the devices for a long time. I put development in parentheses as I can't help thinking it simply represents where battery valves would have been in about the early/mid 'sixties if the transistor hadn't appeared. Indeed, I suspect that tiny valves/thermionic ICs were on quite a few drawing boards and development labs on both sides of the Cold War but we just didn't get the full story.

Not so long ago you could get a VFD from Maplins in a mixed bag of displays for £4.99. I think they may still have them, best to look in store rather than online as at least you get to pick the bag containing the display you want! I bought some to repair a VFD clock that I stupidly dropped and broke